When producing sausages, a pasty mass is by use of a filling machine pushed via a hopper and a vane cell pump into a stuffing tube, where the pasty mass is then extruded, for example, from the stuffing tube into a sausage casing. In order to preserve food, in particular pasty mass such as sausage meat, as much air as possible is removed from these masses. A vacuum pump is for this purpose connected to the vane cell pump for the paste mass in order to evacuate the vanes of the vane cell pump. Respective filling machines or vane cell pumps are shown, for example, in EP 1 044 612 and EP 1 837 524. FIG. 11 shows a cross-sectional view through a respective vane cell pump. It is there evident that an evacuation opening is provided in the side wall of the vane cell pump and leads via a channel to the vacuum pump.
It happens when evacuating the delivery cells, however, that parts of the pasty mass are dragged along in the direction of the vacuum pump. A collection container is provided for this reason between the delivery pump and the vacuum pump to collect entrained pasty mass, dirt and water. Also when cleaning the vane cell pump, parts of the conveyed mass, water, and dirt enter into this collection container. The vacuum pump and the air filter disposed upstream thereof can thereby be protected.
The collection container must be emptied and cleaned at regular intervals to prevent the spread of pathogenic organisms and unpleasant odors. It must additionally be prevented that the mass collected in the collection container exceeds a certain filling level, i.e. it must be prevented that the vacuum connection from the delivery pump to the vacuum pump is interrupted (for example, when the mass collected already completely fills the collection container and already rises into the vacuum lines so that the vacuum lines become clogged). Otherwise, there is an undesirable increase in pressure in the delivery cells. In addition, the vacuum channel between the conveying mechanism and the collection device must be cleaned regularly.
It is with conventional filling machines in the ready-to-operate state not possible to inspect the vacuum channel in order to decide at the right point in time whether the vacuum channel needs cleaning.
Accessibility to the vacuum channel was previously only possible from the upper side of the open conveying mechanism. This means that if e.g. a clogged vacuum channel needs to be cleaned, the hopper of the filling machine must first be emptied in order to then pivot upwardly the pivot casing to which the hopper is attached and at the lower end of which the cover of the vane cell pump is located. Any inspection of the vacuum channel is hardly feasible, and monitoring the collection container is cumbersome since, for example, the collection container is to be inspected behind a flap, while the vacuum must be switched off for inspection. Even with the vane cell pump being open, the vacuum channel and/or the collection container cannot be adequately inspected.
The opening for evacuation of the vane is in conventional filling machines located in the side wall of the pump housing. Due to a radial sealing gap between the vane and the vane cell pump housing, pasty mass is dragged along by the rotor and the pump vanes into the evacuation area, i.e. the region in which the evacuation opening is disposed. This dragged along material then deposits on the lateral pump wall in the evacuation region, in particular at the edges of the evacuation opening, and over time clogs the evacuation opening in the pump wall. Moreover, it is possible that the pasty mass is then dragged along also into the vacuum channel and the collection container. The channel can become clogged, so that both evacuation as well as the portioning accuracy deteriorates.
Proceeding from there, the present invention is based on the object to provide a filling machine and a method for filling which enable permanently safe and reliable evacuation of the vane cell chambers and hence of the product.
According to the present invention, the evacuation opening is now located in the pump cover, i.e. suction is effected upwardly and the vane cells are vented upwardly, respectively, so that the suction is effected through the pump cover. The evacuation opening is disposed in the vacuum region and opens into the vane cell chamber. The vane cells move past beneath the evacuation opening. Whenever a pump vane passes by beneath the evacuation opening, the pasty mass, should something have nevertheless been deposited at the pump cover, is entrained by the pump vanes and the bore hole is thereby kept clear. Keeping the evacuation opening clear at the pump cover is possible for the reason that the gap between the pump vane and the pump cover is considerably smaller than the radial gap between the pump wall and pump vane. Clogging of the evacuation opening by pasty mass dragged along is thereby prevented. Moreover, the amount of mass that is dragged along through a vacuum line from the evacuation opening in the direction toward the vacuum pump can be significantly reduced, so that the cleaning effort necessary can be significantly reduced. Adequate evacuation of the vane cells can thereby be permanently ensured, so that adequate and accurate evacuation of the pasty mass can also be ensured at a high portioning accuracy, i.e. process reliability in production can be ensured over a longer period. Any additional components such as wiper plates etc. are not necessary. Negative pressure can according to the invention be generated in the vane cells regardless of fouling and deposits on the side walls of the vane cell pump. Any mass adhering to the cover can be easily wiped from the pump vane so that the bore hole is cleared. Since the opening is located at the top, no fouling can due to gravity drop into the opening. In addition, the evacuation opening according to the invention also enables a separate access way from the top, for example, from the top through the cover of the vane cell pump or through a pivot housing and the cover, without the vane cell pump needing to be opened.
The evacuation opening is connected via a vacuum line to the vacuum pump. This means that a vacuum-tight line is run from the evacuation opening to the vacuum pump. Different line sections are for this connected in a pressure-tight manner or sealed to each other.
The vacuum line comprises e.g. a channel section in the cover and a recess. The recess can be formed in the cover and/or in the pivot housing on which the cover is arranged. The recess can have a larger cross-sectional area than the channel section. An inspection opening is disposed in the upper region of the recess through which the evacuation opening and/or the channel section communicating with the evacuation opening can be inspected, in one example. The degree of fouling of the evacuation opening or the channel section can therewith be inspected in a simple manner from above without the cover of the filling machine needing to be opened.
The vacuum line can also comprise a channel that is with one end in communication with a collection container for pasty mass that is dragged along. Its other end can open into the recess, in particular in its lower region. The vane cell pump is thereby e.g. via the evacuation opening, the channel section, the recess and the further channel in communication with the collection container.
This arrangement can be configured such that the channel and/or of the collection container can be inspected through the inspection opening when the cover is closed. The inspection opening is there facing upwardly so that an operator can inspect the degree of fouling from above. The operator can advantageously via the inspection opening inspect both the channel to the collection container and/or the collection container as well as also the evacuation opening and/or the channel section to the evacuation opening. The degree of fouling can thus be determined in a simple manner. Moreover, the inspection opening also provides access to the respective sections of the vacuum line for cleaning the respective sections without complex measures being necessary. This embodiment therefore provides the advantage that the vane cell pump does not need to be opened when inspecting for fouling, so that, for example, a cover of the vane cell pump together with a pivot housing and a hopper disposed thereon do not need to be pivoted away. The hopper also does not need to be emptied.
According to one embodiment of the present invention, the inspection opening is disposed, for example, in a cover of the vane cell pump. This is the case where the pivot housing on which the hopper is disposed and on the underside of which the cover is attached is in certain types of machines smaller than the cover such that the cover protrudes beyond the pivot housing. But it is also possible that the inspection opening is located in the pivot housing and that a respective recess is then provided at least in the pivot housing into which both the channel to the collection container as well as the channel section to the evacuation opening can open. In order to ensure free visibility into the collection container and into the evacuation opening, there must be at least one respective straight optical path connecting the inspection opening with the inlet to the collection container or to the evacuation opening.
The inspection opening is advantageously formed to be closeable. The inspection opening can by way of a closure element be closed and may also be reopened. The closure element is in one example configured as an axially movable piston. The closure element can also comprise an inspection glass so that the operator can inspect the channel and/or the collection container or the channel section and/or the evacuation opening also during an ongoing process through the inspection glass and immediately become aware of excessive fouling.
The piston is advantageously arranged to be axially movable in the recess such that in a lower position, it closes either the channel which is in communication with the collection container and/or the further channel section which leads to the evacuation opening, i.e. separates the channel from the further channel section.
The axially movable piston can also be completely removed from the recess, so that, for example, the channel can be better inspected and cleaned. It is also possible to move the axially movable piston so far upwards that the channel and the further channel section can be vented. In the inserted state, the piston seals the recess from the exterior. The piston can be axially moved manually, for example, by use of a thread, a bayonet closure, a toggle lever, etc.
However, it is also possible to provide a driven closure cylinder which separates the vacuum connection between the vacuum pump and the vane cell pump, where the closure cylinder can be retracted—when viewed from a position in the vertical direction—in one example, below the cover into the vacuum line, i.e. into the channel.
According to another embodiment, at least one sensor is integrated in the closure element and/or into the cover of the vane cell pump, in particular for measuring the temperature and/or the pressure and/or the density and/or of the air content. An optical sensor can also be integrated in the closure element which optically detects, for example, the channel and/or the collection container and/or the channel section and/or the evacuation opening and represents it on a display. The sensor signals can be supplied to the control system of the filling machine and evaluated there, and used for automated process control and optimization.
The vacuum channel is sealed in a region between the cover and the pivot housing. This means that either a sealing device is provided between the cover and the pivot housing, or that, for example, a tube is run in a pressure-tight manner from the evacuation opening through the cover and the pivot housing.
The sensor is one example a pressure sensor and may be arranged in the closure element. It can comprise a display element that is movable in dependence of the pressure in the vane cell chamber. This means that the display element is in the vertical direction moved upwardly in dependence of the pressure out from the closure element and also downwardly into the closure element, so that an operator can monitor the pressure condition in the vane cell chamber in a simple manner. The display element is there in particular configured as a slide that is adjustable in height. The display element is advantageously disposed in the upper region of a channel in the closure element and is held by a spring in a certain position, where the display element with decreasing pressure in the vane cell pump moves downwardly against the spring force. The display element can with increased pressure extend above the surface of the closure element, so that the operator can easily recognize the position of the display element. The slide position can be detected by sensors and the signal supplied to the controller and evaluated by the latter.
In the method according to the invention for filling a pasty mass, the empty vane cells returning to the inlet of the vane cell pump are evacuated via an evacuation opening in the cover of the housing of the vane cell pump.
According to one embodiment, a groove-shaped depression in the vacuum region is formed in the flat surface of the cover facing the pump interior and the evacuation opening is arranged outside the depression in the vacuum region.